"I think toward the end of the Olympics you get mentally and physically tired, just like drained. I try to fight through as much as I can," said Douglas, reported the Associated Press.

It was a blow for the 16-year-old, who has been one of the stars of London 2012, winning the prestigious individual all-around title and playing a key role in the American women's team win. She will compete Tuesday in her last event, the individual balance beam finals.

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Taking gold was Russia's Aliya Mustafina, who came back form a knee injury to score the first gold for the Russian womens gymnasts. Defending gold medalist He Kexin of China took silver. Great Britain's Elizabeth Tweddle, who had been favored for gold, took the bronze after stumbling on her dismount.

Douglas' work is far from over, however, as she's scheduled to compete Tuesday in the finals for the beam. She had the second-best qualifying score for the beam, tied with Komova, behind Sui Lu of China, who won gold in the event at last year's world championships.

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In the men's rings competition, Brazilian Arthur Zanetti's unexpectedly took gold, a surprise for Chen Yibing, captain of the Chinese men's gymnastics team, 2008 gold medalist and four-time world champion, with Chen settling for silver. Matteo Morandi of Italy took bronze.

In the men's vault, Yang Hak-Seon of South Korea unleashed "The Yang," which involves three twists, the hardest trick in the sport, but it was punctuated by two large steps. Still, the degree of difficulty gave him a 16.466 for his first vault. His next vault was only a double twist, but he nailed the landing to take gold with a 16.533. Russia's Denis Ablyazin won silver, and Ukrainian Igor Radivilov took bronze.

American Samuel Mikulak, who won the NCAA men's individual all-around gymnastics championshiplast year, was the lone American competing in the vault. His second vault was among the best of the competition finishing tied for sixth with a score of 16.10, but his overall score was not enough to medal.